In the production of disk-shaped information carriers, for example, compact disks (CD's) and especially information carriers for reproduction of audio and video signals, for the storage of data and the like, it is known to provide the disk at an upper surface thereof with a so called stacking bead.
This bead at the upper surface is coaxial with an annular recess at the lower surface which is defined in part within the injection mold by a shoulder provided on a sleeve which serves in the mold to overhang a matrix or forming a disk constituting part of the die or mold against which the material of the information carrier is injection molded.
It has been found, in the use of such dies that the injection molding of the information carrier disk produces so called schlieren or streaks which may render the disk unusable as in information carrier.
Efforts have been made to reduce the formation of such streaks or eliminate streaking by a slow injection of the synthetic resin material into the injection-molding or die cavity. This, however, results in a long cycling time of the mold and the apparatus, a low production rate and a poor productivity of the equipment. This method, therefore, has been found to be uneconomical.